Thanks Liz and David Correct Liz and David, as u calculate the collection day is Day zero one day will be complete next day, so we start count from 17 and 42 days falls on 2/27. We had a visitor last week and he objected our count. He started count from 16 Jan (Collection Date) and told platelet (5 days) shall expire on 20 Jan, whereas I said 21 Jan. I did not find it in the books. Do u have a reference?